ILC3s Possess Microbiota-Inducible Acute Wound Healing Potential 2299679

Abstract Introduction Commensal bacteria are key mediators of intestinal inflammation, yet distinguishing beneficial species from potential pathobionts remains challenging. Identification and characterization of human gut commensals could provide insights to design therapeutics to attenuate and heal mucosal inflammation. Methods To identify protective human gut commensals, we collected stool from healthy human donors and colonized germ-free (GF) mice. We used antibiotic depletion to enrich for subsets of bacteria and assessed inflammatory and protective potential in DSS-induced colitis and IL-10KO models. Candidate wound-healing stimulators were isolated and examined in vitro and in vivo. Results GF mice colonized with a human microbiome showed strong protection from lethal DSS challenge, whereas all GF controls succumbed by day 12. These gavaged mice exhibited increased IL-22 production from ILC3s. However, the same human microbiota triggered robust IFNy+, IL-17A+, and IFNy/IL-17A+ CD4+ T cells in IL-10KO mice. Antibiotic treatment reduced bacterial diversity but maintained high IL-22 production and full protection from DSS. Cecal contents from these antibiotic-treated mice did not induce pro-inflammatory T cells in IL-10KO recipients, suggesting enrichment of protective species. From this limited community we isolated Klebsiella oxytoca, which when monocolonized in GF mice conferred strong protection from DSS, reduced histologic damage, and enhanced crypt proliferation. Using mice lacking IL-1R1 and/or IL-23R specifically on ILC3s, we found that K. oxytoca primarily signals through IL-1R1 to induce IL-22 from ILC3s. Conclusion These findings identify K. oxytoca as a human commensal that potently stimulates ILC3-depedent IL-22 to limit intestinal injury and promote epithelial regeneration. Ongoing work is testing its therapeutic potential in radiation-induced enteritis and screening additional human derived bacterial candidates for wound healing activity using an in-vitro screening system. Funding Source n/a Topic Categories Mucosal and Regional Immunology (MUC)